In the long term evolution infrastructure, a UE can be in one of two radio resource control (RRC) states. These are LTE_IDLE and LTE_ACTIVE.
The UE can be configured for discontinuous reception (DRX) in both the LTE_IDLE and the LTE_ACTIVE states. DRX allows the UE to synchronize its listening period to a known paging cycle of the network. By synchronizing the listening period with acceptable transmission times from the network, the UE can turn off its radio transceiver when the network will not schedule transmissions, thereby significantly saving battery resources. As will be appreciated by those skilled in the art, unless a UE is used extensively, a large drain on its battery comes from the standby cycle in which it monitors the paging channel (or control channels) and measures serving and neighboring cells. DRX parameters allow the mobile to synchronize with the network and to know that it will not receive another signal until a specified time has elapsed.
Utilizing DRX in an IDLE state is performed in present UMTS systems and is done by the network signaling to the UE a DRX parameter and synchronizing the UE and the network.
In an ACTIVE state however, various issues exist for turning off the receiver based on a DRX parameter. This includes the fact that only network controlled handover is allowed in the LTE_ACTIVE state. Also, other issues include efficient signaling of activation and deactivation of DRX, measurement requirements of network signals during the DRX, handling of missed handover opportunities, and issues dealing with the length of the DRX value in which entity in the network can request DRX activation and reconfiguring the DRX period.
Further issues involve configuration and control of various timers for long DRX.